Astronomy C

[Avogadro]

I'll try (Click to Show Hidden Text)

Dimmer

[jonboyage]

Hopefully I remember this correctly (Click to Show Hidden Text)

dimmer drops faster?

I messed up, you were correct, this is called the luminosity decline rate relation.

[Unome]

Hopefully I remember this correctly (Click to Show Hidden Text)

dimmer drops faster?

I don't think so :/ (Click to Show Hidden Text)

I have read in the past that the brighter ones drop faster

I looked it up just now and this is what I found (Click to Show Hidden Text)

[quote="Wikipedia - Phillips relationship"]They found that the faster the supernova faded from maximum light, the fainter its peak magnitude was[/quote]

[jonboyage]

Yeah you were right sorry, I checked online right after I posted just to make sure and I found that the dimmer ones drop faster.
Do you want to ask the next one?

[Unome]

Yeah you were right sorry, I checked online right after I posted just to make sure and I found that the dimmer ones drop faster.
Do you want to ask the next one?

Sure. Here's a tie-in math question. (Click to Show Hidden Text)

A type Ia supernova is discovered in a distant galaxy. Its maximum apparent magnitude is measured at 18.4. After monitoring the supernova for 15 days, the B band magnitude drops by 1.2.
1. What is the theoretical absolute luminosity of a type Ia supernova originating from a single progenitor?
2. Calculate the distance to the supernova based on this theoretical absolute magnitude.
3. Determine the speed at which the galaxy containing the supernova is receding. Use a Hubble constant of 70 km^-1*Mpc^-1
4. Based on the luminosity decline, determine the actual absolute magnitude of the supernova.
5. Recalculate the distance and recessional velocity based on the actual absolute magnitude.

[jonboyage]

Yeah you were right sorry, I checked online right after I posted just to make sure and I found that the dimmer ones drop faster.
Do you want to ask the next one?

Sure. Here's a tie-in math question. (Click to Show Hidden Text)

A type Ia supernova is discovered in a distant galaxy. Its maximum apparent magnitude is measured at 18.4. After monitoring the supernova for 15 days, the B band magnitude drops by 1.2.
1. What is the theoretical absolute luminosity of a type Ia supernova originating from a single progenitor?
2. Calculate the distance to the supernova based on this theoretical absolute magnitude.
3. Determine the speed at which the galaxy containing the supernova is receding. Use a Hubble constant of 70 km^-1*Mpc^-1
4. Based on the luminosity decline, determine the actual absolute magnitude of the supernova.
5. Recalculate the distance and recessional velocity based on the actual absolute magnitude.

Answer (Click to Show Hidden Text)

1. -19.3
2. 346.7mpc
3. 24271.6km/s
4. -18.4884
5. 238.6mpc; 16702.4km/s

[Bob_117]

Yeah you were right sorry, I checked online right after I posted just to make sure and I found that the dimmer ones drop faster.
Do you want to ask the next one?

Sure. Here's a tie-in math question. (Click to Show Hidden Text)

A type Ia supernova is discovered in a distant galaxy. Its maximum apparent magnitude is measured at 18.4. After monitoring the supernova for 15 days, the B band magnitude drops by 1.2.
1. What is the theoretical absolute luminosity of a type Ia supernova originating from a single progenitor?
2. Calculate the distance to the supernova based on this theoretical absolute magnitude.
3. Determine the speed at which the galaxy containing the supernova is receding. Use a Hubble constant of 70 km^-1*Mpc^-1
4. Based on the luminosity decline, determine the actual absolute magnitude of the supernova.
5. Recalculate the distance and recessional velocity based on the actual absolute magnitude.

Answer (Click to Show Hidden Text)

1. -19.3
2. 346.7mpc
3. 24271.6km/s
4. -18.4884
5. 238.6mpc; 16702.4km/s

Sorry for jumping in but I have a question. How did you calculate the absolute magnitude in question 4? I've looked up luminosity decline rate and a couple other things and I haven't been able to find anything. Thanks in advance.

[jonboyage]

Sure. Here's a tie-in math question. (Click to Show Hidden Text)

A type Ia supernova is discovered in a distant galaxy. Its maximum apparent magnitude is measured at 18.4. After monitoring the supernova for 15 days, the B band magnitude drops by 1.2.
1. What is the theoretical absolute luminosity of a type Ia supernova originating from a single progenitor?
2. Calculate the distance to the supernova based on this theoretical absolute magnitude.
3. Determine the speed at which the galaxy containing the supernova is receding. Use a Hubble constant of 70 km^-1*Mpc^-1
4. Based on the luminosity decline, determine the actual absolute magnitude of the supernova.
5. Recalculate the distance and recessional velocity based on the actual absolute magnitude.

Answer (Click to Show Hidden Text)

1. -19.3
2. 346.7mpc
3. 24271.6km/s
4. -18.4884
5. 238.6mpc; 16702.4km/s

Sorry for jumping in but I have a question. How did you calculate the absolute magnitude in question 4? I've looked up luminosity decline rate and a couple other things and I haven't been able to find anything. Thanks in advance.

I simply used the formula for the Philips relationship which you can easily find the Wikipedia page for. The formula is this: M_max(B) = -21.726 + 2.698Δm_15(B). This formula is very specific to the scenario given here: after 15 days, the B-band magnitude drops by 1.2. Hope that helps!

[Unome]

Answer (Click to Show Hidden Text)

1. -19.3
2. 346.7mpc
3. 24271.6km/s
4. -18.4884
5. 238.6mpc; 16702.4km/s

Sorry for jumping in but I have a question. How did you calculate the absolute magnitude in question 4? I've looked up luminosity decline rate and a couple other things and I haven't been able to find anything. Thanks in advance.

I simply used the formula for the Philips relationship which you can easily find the Wikipedia page for. The formula is this: M_max(B) = -21.726 + 2.698Δm_15(B). This formula is very specific to the scenario given here: after 15 days, the B-band magnitude drops by 1.2. Hope that helps!

Sorry, forgot about this during prep for regionals. Correct, your turn.

[Magikarpmaster629]

I'll pick this up then.

Some standard math:

Star A has a temperature of 6400 K.
1. Calculate its peak wavelength in nm.
2. The real wavelength is measured to be 480 nm. What is the recessional velocity of the star in m/s?
3. Is this number reasonable?
4. Star A is part of system AB, which has an apparent magnitude of 6.4 and an absolute magnitude of 1.99. Star B has a luminosity of 5.0 solar luminosities. What is the radius of star A in solar radii?
5. How far away is system AB in parsecs, light years, AU, and meters?